To obtain a peripheral aligner and a peripheral exposure method by which need for exchanging the mask of the peripheral aligner is eliminated, irradiation light leaked from light irradiation width is surely eliminated, the ridgeline of a peripheral position can be processed to be like a knife edge and the peripheral position of a work which can properly deal with such constitution that one and the other peripheral positions of the work are different can be exposed without requiring a rotation mechanism of work and the like.

This aligner exposes the peripheral position Ws of the pattern exposure part of the work W. In this case, it is constituted as the peripheral aligner 1 provided with a light source part 4 emitting the irradiation light including ultraviolet rays having a prescribed wavelength, a housing part 8 housing the light source part 4, a lens 5 (6) arranged at the housing part 8 so as to project the irradiation light and a shutter mechanism 7 arranged at the housing part 8 side in an irradiation path up to the work from the light source part 4 so as to freely variably form the light irradiation width of the irradiation light as the mask width.